Goals: Like its sister mission, Mars 7 (which arrived at Mars three days earlier but failed to deliver its lander) Mars 6 was intended to place a lander on Mars. The bus was to fly by the planet, taking measurements as it passed.

Accomplishments: The descent module transmitted 224 seconds of data-the first data returned from the Martian atmosphere-but much of it was unreadable because of a flaw in a computer chip. Contact was lost moments before the presumed landing. The bus that delivered the lander to Mars transmitted scientific information during its brief flyby of the planet.